git-rev-parse(1) Manual Page

NAME

git-rev-parse -
Pick out and massage parameters

SYNOPSIS

git-rev-parse [ --option ] <args>…

DESCRIPTION

Many git porcelainish commands take mixture of flags
(i.e. parameters that begin with a dash -) and parameters
meant for underlying git-rev-list command they use internally
and flags and parameters for other commands they use as the
downstream of git-rev-list. This command is used to
distinguish between them.

OPTIONS

Only meaningful in --parseopt mode. Tells the option parser to echo
out the first -- met instead of skipping it.

--revs-only

Do not output flags and parameters not meant for
git-rev-list command.

--no-revs

Do not output flags and parameters meant for
git-rev-list command.

--flags

Do not output non-flag parameters.

--no-flags

Do not output flag parameters.

--default <arg>

If there is no parameter given by the user, use <arg>
instead.

--verify

The parameter given must be usable as a single, valid
object name. Otherwise barf and abort.

--sq

Usually the output is made one line per flag and
parameter. This option makes output a single line,
properly quoted for consumption by shell. Useful when
you expect your parameter to contain whitespaces and
newlines (e.g. when using pickaxe -S with
git-diff-\*).

--not

When showing object names, prefix them with ^ and
strip ^ prefix from the object names that already have
one.

--symbolic

Usually the object names are output in SHA1 form (with
possible ^ prefix); this option makes them output in a
form as close to the original input as possible.

--symbolic-full-name

This is similar to --symbolic, but it omits input that
are not refs (i.e. branch or tag names; or more
explicitly disambiguating "heads/master" form, when you
want to name the "master" branch when there is an
unfortunately named tag "master"), and show them as full
refnames (e.g. "refs/heads/master").

--all

Show all refs found in $GIT_DIR/refs.

--branches

Show branch refs found in $GIT_DIR/refs/heads.

--tags

Show tag refs found in $GIT_DIR/refs/tags.

--remotes

Show tag refs found in $GIT_DIR/refs/remotes.

--show-prefix

When the command is invoked from a subdirectory, show the
path of the current directory relative to the top-level
directory.

--show-cdup

When the command is invoked from a subdirectory, show the
path of the top-level directory relative to the current
directory (typically a sequence of "../", or an empty string).

--git-dir

Show $GIT_DIR if defined else show the path to the .git directory.

--is-inside-git-dir

When the current working directory is below the repository
directory print "true", otherwise "false".

--is-inside-work-tree

When the current working directory is inside the work tree of the
repository print "true", otherwise "false".

--is-bare-repository

When the repository is bare print "true", otherwise "false".

--short, --short=number

Instead of outputting the full SHA1 values of object names try to
abbreviate them to a shorter unique name. When no length is specified
7 is used. The minimum length is 4.

SPECIFYING REVISIONS

A revision parameter typically, but not necessarily, names a
commit object. They use what is called an extended SHA1
syntax. Here are various ways to spell object names. The
ones listed near the end of this list are to name trees and
blobs contained in a commit.

The full SHA1 object name (40-byte hexadecimal string), or
a substring of such that is unique within the repository.
E.g. dae86e1950b1277e545cee180551750029cfe735 and dae86e both
name the same commit object if there are no other object in
your repository whose object name starts with dae86e.

An output from git-describe; i.e. a closest tag, followed by a
dash, a g, and an abbreviated object name.

A symbolic ref name. E.g. master typically means the commit
object referenced by $GIT_DIR/refs/heads/master. If you
happen to have both heads/master and tags/master, you can
explicitly say heads/master to tell git which one you mean.
When ambiguous, a <name> is disambiguated by taking the
first match in the following rules:

if $GIT_DIR/<name> exists, that is what you mean (this is usually
useful only for HEAD, FETCH_HEAD and MERGE_HEAD);

otherwise, $GIT_DIR/refs/<name> if exists;

otherwise, $GIT_DIR/refs/tags/<name> if exists;

otherwise, $GIT_DIR/refs/heads/<name> if exists;

otherwise, $GIT_DIR/refs/remotes/<name> if exists;

otherwise, $GIT_DIR/refs/remotes/<name>/HEAD if exists.

A ref followed by the suffix @ with a date specification
enclosed in a brace
pair (e.g. {yesterday}, {1 month 2 weeks 3 days 1 hour 1
second ago} or {1979-02-26 18:30:00}) to specify the value
of the ref at a prior point in time. This suffix may only be
used immediately following a ref name and the ref must have an
existing log ($GIT_DIR/logs/<ref>).

A ref followed by the suffix @ with an ordinal specification
enclosed in a brace pair (e.g. {1}, {15}) to specify
the n-th prior value of that ref. For example master@{1}
is the immediate prior value of master while master@{5}
is the 5th prior value of master. This suffix may only be used
immediately following a ref name and the ref must have an existing
log ($GIT_DIR/logs/<ref>).

You can use the @ construct with an empty ref part to get at a
reflog of the current branch. For example, if you are on the
branch blabla, then @{1} means the same as blabla@{1}.

A suffix ^ to a revision parameter means the first parent of
that commit object. ^<n> means the <n>th parent (i.e.
rev^
is equivalent to rev^1). As a special rule,
rev^0 means the commit itself and is used when rev is the
object name of a tag object that refers to a commit object.

A suffix ~<n> to a revision parameter means the commit
object that is the <n>th generation grand-parent of the named
commit object, following only the first parent. I.e. rev~3 is
equivalent to rev^^^ which is equivalent to
rev^1^1^1. See below for a illustration of
the usage of this form.

A suffix ^ followed by an object type name enclosed in
brace pair (e.g. v0.99.8{caret}\{commit\}) means the object
could be a tag, and dereference the tag recursively until an
object of that type is found or the object cannot be
dereferenced anymore (in which case, barf). rev{caret}0
introduced earlier is a short-hand for rev{caret}\{commit\}.

A suffix ^ followed by an empty brace pair
(e.g. v0.99.8{caret}\{\}) means the object could be a tag,
and dereference the tag recursively until a non-tag object is
found.

A colon, followed by a slash, followed by a text: this names
a commit whose commit message starts with the specified text.
This name returns the youngest matching commit which is
reachable from any ref. If the commit message starts with a
!, you have to repeat that; the special sequence :/!,
followed by something else than ! is reserved for now.

A suffix : followed by a path; this names the blob or tree
at the given path in the tree-ish object named by the part
before the colon.

A colon, optionally followed by a stage number (0 to 3) and a
colon, followed by a path; this names a blob object in the
index at the given path. Missing stage number (and the colon
that follows it) names a stage 0 entry. During a merge, stage
1 is the common ancestor, stage 2 is the target branch’s version
(typically the current branch), and stage 3 is the version from
the branch being merged.

Here is an illustration, by Jon Loeliger. Both commit nodes B
and C are parents of commit node A. Parent commits are ordered
left-to-right.

SPECIFYING RANGES

History traversing commands such as git-log operate on a set
of commits, not just a single commit. To these commands,
specifying a single revision with the notation described in the
previous section means the set of commits reachable from that
commit, following the commit ancestry chain.

To exclude commits reachable from a commit, a prefix {caret}
notation is used. E.g. "{caret}r1 r2" means commits reachable
from r2 but exclude the ones reachable from r1.

This set operation appears so often that there is a shorthand
for it. "r1..r2" is equivalent to "{caret}r1 r2". It is
the difference of two sets (subtract the set of commits
reachable from r1 from the set of commits reachable from
r2).

A similar notation "r1\...r2" is called symmetric difference
of r1 and r2 and is defined as
"r1 r2 --not $(git-merge-base --all r1 r2)".
It is the set of commits that are reachable from either one of
r1 or r2 but not from both.

Two other shorthands for naming a set that is formed by a commit
and its parent commits exists. r1{caret}@ notation means all
parents of r1. r1{caret}! includes commit r1 but excludes
its all parents.

PARSEOPT

In --parseopt mode, git-rev-parse helps massaging options to bring to shell
scripts the same facilities C builtins have. It works as an option normalizer
(e.g. splits single switches aggregate values), a bit like getopt(1) does.

It takes on the standard input the specification of the options to parse and
understand, and echoes on the standard output a line suitable for sh(1)eval
to replace the arguments with normalized ones. In case of error, it outputs
usage on the standard error stream, and exits with code 129.

Input Format

git-rev-parse --parseopt input format is fully text based. It has two parts,
separated by a line that contains only --. The lines before the separator
(should be more than one) are used for the usage.
The lines after the separator describe the options.

Each line of options has this format:

<opt_spec><arg_spec>? SP+ help LF

<opt_spec>

its format is the short option character, then the long option name
separated by a comma. Both parts are not required, though at least one
is necessary. h,help, dry-run and f are all three correct
<opt_spec>.

<arg_spec>

an <arg_spec> tells the option parser if the option has an argument
(=), an optional one (? though its use is discouraged) or none
(no <arg_spec> in that case).

The remainder of the line, after stripping the spaces, is used
as the help associated to the option.

Blank lines are ignored, and lines that don’t match this specification are used
as option group headers (start the line with a space to create such
lines on purpose).